The present invention relates in general to vapor cycle piston heat engines, and more particularly to a method of operation of the vapor cycle of such an engine.
The present invention is useful for those heat engine applications requiring the highest practicable efficiency, notably portable applications for automobile power trains. Steam vapor cycle plants for automobile power trains enable a wide range of fuels to be employed with less atmospheric pollution than would result from internal combustion heat engine. It is projected that specific fuel costs and absolute fuel costs may be lower with such an engine than is presently the case for the internal combustion engine. To be successful in portable applications, the specific fuel consumption must be low. Accordingly, the engine itself must be made efficient and must be lightweight so as to keep the mass to be transported to a minimum.
In the patent to Marion K. Harris, U.S. Pat. No. 3,568,444, granted on Mar. 9, 1971, there is disclosed a method of operating a vapor cycle power plant, which includes the steps of regeneration, recompression and reheating to increase the net work output and efficiency.
The patent to John Gordon Davoud, U.S. Pat. No. 3,716,990, issued on Feb. 20, 1973, disclosed a condensable vapor power producing system in which a condensable fluid is heated to a predetermined temperature at a predetermined pressure and has a given entropy. Part of the steam is expanded in a work producing zone to a lower pressure and the condensed. The remaining part of the steam is expanded in a second zone. Water is then added to the expanded steam of the second zone to form a weight of steam greater than that introduced into the second zone, but at a lower entropy. The work of expansion in the second zone is used to compress the steam in the second zone.
The patent to John Gordon Davoud, U.S. Pat. No. 3,772,883, issued on Nov. 20, 1973, discloses an external combustion power producing cycle in which a condensable fluid is heated to a vapor state. The heated vapor is separated into two portions without changing the temperature, pressure, entropy, enthalpy, or specific volume state thereof. One portion is expanded isentropically in a first zone to a lower pressure in a non-compression, expansion-only cylinder and is removed from the cylinder and passed into a condenser. The other portion is expanded isentropically in a second zone in a series of expansion and compression cylinders. The weight equivalent of the one condensed portion of the fluid in liquid form of the first zone is introduced into the other portion of the fluid in the second zone. The mixture in the second zone is compressed isentropically to the maximum working pressure. The compressed fluid is reheated and re-expanded.
The patent to John Gordon Davoud, U.S. Pat. No. 3,798,908, issued on Mar. 26, 1974, discloses an external combustion power producing cycle in which condensable fluid is heated to a vapor state. The heated vapor is expanded isentropically. After expansion, the fluid is separated into two portions without changing the temperature, pressure, entropy, enthalpy, or its specific volume state. After the expanded fluid has been separated into two portions, one portion is condensed and the weight equivalent thereof is added, in liquid form, to the other portion of the expanded fluid. The mixture, which has a lower entropy than the fluid prior to the introduction of liquid, is compressed to the desired operating pressure.